Re: cleaning a .22 rifle
i used to clean my barrel, but after getting into the rimfire stuff a few years ago, i was told the same thing - not to clean it. of course i didn't believe it and have bad mojo about having a "dirty" gun in the safe.
after running a test of cleaning vs. letting it go, letting it go does improve accuracy.
being the curious sort, i had to find out why....this is what i learned:
most of your "lesser" ammos are manufactured by the gross, and consistancy of the bullet diameter differs from round to round as they pump them out of the factory. different lots, different machines, machines going out of calibration, etc all cause slight differences / defects / deformities. the gunk, fouling, and leading in the barrel actually acts like a "shim" for these differences which helps out overall to make a tighter seal between the barrel lands and grooves and the bullet.
this is also the facts behind why lubricated ammo usually has an edge over non-lubricated ammo - the "grease" fills those spaces for a tighter seal.
also (not as much with the annies as compared to "lesser" manufacturers) many rimfire barrels are produced the same way as the "lesser" ammos - not quite as much tolerances which allow different (all though minute) differencess in the barrel diameter, depth of the grooves and lands, variances in the chambers, etc. as they are mass produced. by allowing the barrel to stay "leaded" or fouled, those small descrepencies are filled in making a tighter seal by default. even small pits or defects in the metal are filled in by the lead, acting like "barrel bondo".
there is a point where it gets too much, then it's time to get rid of the gunk and start all over again building that desirable film of fouling that actually adds to accuracy.